Week 7 textbook

Question 1

electrophile

Answer 1

atom or group that’s attracted to electrons and tends to accept electrons to make bonds

-electrophiles attract Nuc.

Question 2

nucleophiles

Answer 2

atoms or groups that donate electrons to form bonds

-form new bonds by SHARING a pair of electrons with an electrophilic site

Question 3

hydride nucleophile

Answer 3

simplest nucleophile that can be added to a carbonyl group is the hydride ion (H−)

the small size of the hydride ion makes it a very poor nucleophile (hydride is, however, a very strong base)

Question 4

grignard reagent

Answer 4

contains a carbon bonded to a magnesium atom

Question 5

how is grignard reagent formed?

Answer 5

by exposing an ethereal solution of an organic halide to magnesium metal (not stable in other solvents)

Question 6

carbanions

Answer 6

negatively charged carbon

Question 7

effect of electropositive Mg atom on GR

Answer 7

Because the magnesium atom is very electropositive, Grignard reagents have a highly polarized carbon-magnesium bond and behave as if there is a full negative charge on the carbon atom

such reagents are called carbanions, very strong bases that have the corresponding alkane as the conjugate acid

Question 8

acid-base rxns involving GR

Answer 8

fast and highly exothermic
-rapidly removes a proton from any functional group that contains a hydrogen with a pKa lower than the GR’s conj acidd

Question 9

hydrolysis in GR

Answer 9

Once the addition of the Grignard to the carbonyl group has been completed, the magnesium alkoxide is treated with a solution of dilute acid in water

This process BREAKS the oxygen-magnesium bond, producing an alcohol
-this rxn called ­hydrolysis, because water (hydro) is breaking (lysing) a bond: the oxygen-magnesium bond in this example